Zinc

I don't get it. I understand the break in reasons. But once an engine is broken in the slippery the oil the better. So a lifter, bearings, etc all ride on a hydraulic wedge of oil (except at startup when you have no oil pressure.) Once your wear pattern is established slippery should be better and cause less wear on your camshaft and bearings.
With that in mind it would follow that synthetic, regardless of zinc content, would be the best thing for an established engine. As long as the hydraulic wedge is doing it's job, I can't understand what roll zinc would play in the life of your engine past break in.

Is it possible that the metal that they use for aftermarket camshafts is too soft for modern oil? You could get away with it because the oil would cover up the hardness or lack off used in the camshaft?

Dan...